skip completion if client closed stream

pkg/analysis_server/lib/src/services/completion/dart_completion_manager.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library services.completion.dart;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/completion/arglist_computer.dart';
@@ skipping 98 matching lines @@
   }
 
   /**
    * If there is remaining work to be done, then wait for the unit to be
    * resolved and request that each remaining computer finish their work.
    */
   void computeFull(DartCompletionRequest request,
       List<DartCompletionComputer> todo) {
     request.performance.logStartTime('waitForAnalysis');
     waitForAnalysis().then((CompilationUnit unit) {
+      if (controller.isClosed) {
+        return;
+      }
       request.performance.logElapseTime('waitForAnalysis');
       if (unit == null) {
         sendResults(request, true);
         return;
       }
       request.performance.logElapseTime('computeFull', () {
         request.unit = unit;
         request.node = new NodeLocator.con1(request.offset).searchWithin(unit);
         int count = todo.length;
         todo.forEach((DartCompletionComputer c) {
@@ skipping 28 matching lines @@
       if (!todo.isEmpty) {
         computeFull(request, todo);
       }
     });
   }
 
   /**
    * Send the current list of suggestions to the client.
    */
   void sendResults(DartCompletionRequest request, bool last) {
+    if (controller.isClosed) {
+      return;
+    }
     controller.add(
         new CompletionResult(
             request.replacementOffset,
             request.replacementLength,
             request.suggestions,
             last));
     if (last) {
       controller.close();
     }
   }
@@ skipping 97 matching lines @@
   _ReplacementOffsetBuilder(this.request) {
     request.replacementOffset = request.offset;
     request.replacementLength = 0;
   }
 
   visitSimpleIdentifier(SimpleIdentifier node) {
     request.replacementOffset = node.offset;
     request.replacementLength = node.length;
   }
 }